全文获取类型
收费全文 | 33656篇 |
免费 | 1127篇 |
国内免费 | 256篇 |
专业分类
化学 | 22937篇 |
晶体学 | 230篇 |
力学 | 837篇 |
数学 | 5562篇 |
物理学 | 5473篇 |
出版年
2023年 | 171篇 |
2021年 | 391篇 |
2020年 | 531篇 |
2019年 | 504篇 |
2018年 | 388篇 |
2017年 | 384篇 |
2016年 | 849篇 |
2015年 | 745篇 |
2014年 | 831篇 |
2013年 | 1806篇 |
2012年 | 1923篇 |
2011年 | 2426篇 |
2010年 | 1186篇 |
2009年 | 1027篇 |
2008年 | 2075篇 |
2007年 | 2092篇 |
2006年 | 2083篇 |
2005年 | 1934篇 |
2004年 | 1653篇 |
2003年 | 1446篇 |
2002年 | 1334篇 |
2001年 | 370篇 |
2000年 | 346篇 |
1999年 | 288篇 |
1998年 | 266篇 |
1997年 | 327篇 |
1996年 | 439篇 |
1995年 | 367篇 |
1994年 | 330篇 |
1993年 | 320篇 |
1992年 | 291篇 |
1991年 | 264篇 |
1990年 | 233篇 |
1989年 | 234篇 |
1988年 | 252篇 |
1987年 | 224篇 |
1986年 | 194篇 |
1985年 | 381篇 |
1984年 | 357篇 |
1983年 | 267篇 |
1982年 | 334篇 |
1981年 | 344篇 |
1980年 | 322篇 |
1979年 | 300篇 |
1978年 | 278篇 |
1977年 | 257篇 |
1976年 | 215篇 |
1975年 | 235篇 |
1974年 | 231篇 |
1973年 | 226篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
Tao Wang Dr. Yuzhou Wu Dr. Seah Ling Kuan Oliver Dumele Dr. Markus Lamla Dr. David Y. W. Ng Matthias Arzt Jessica Thomas Jan O. Mueller Prof. Dr. Christopher Barner‐Kowollik Prof. Dr. Tanja Weil 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):228-238
A disulfide intercalator toolbox was developed for site‐specific attachment of a broad variety of functional groups to proteins or peptides under mild, physiological conditions. The peptide hormone somatostatin (SST) served as model compound for intercalation into the available disulfide functionalization schemes starting from the intercalator or the reactive SST precursor before or after bioconjugation. A tetrazole–SST derivative was obtained that undergoes photoinduced cycloaddition in mammalian cells, which was monitored by live‐cell imaging. 相似文献
24.
A model for the mechanics of woven fabrics is developed in the framework of two-dimensional elastic surface theory. Thickness effects are modeled indirectly in terms of appropriate constitutive equations. The model accounts for the strain of the fabric and additional effects associated with the normal bending, geodesic bending, and twisting of the constituent fibers. 相似文献
25.
26.
Ivan Dragičević Dr. Danijela Barić Dr. Borislav Kovačević Prof. Bernard T. Golding Dr. David M. Smith 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(16):6132-6143
Model studies of prebiotic chemistry have revealed compelling routes for the formation of the building blocks of proteins and RNA, but not DNA. Today, deoxynucleotides required for the construction of DNA are produced by reduction of nucleotides catalysed by ribonucleotide reductases, which are radical enzymes. This study considers potential non‐enzymatic routes via intermediate radicals for the ancient formation of deoxynucleotides. In this context, several mechanisms for ribonucleotide reduction, in a putative H2S/HS. environment, are characterized using computational chemistry. A bio‐inspired mechanistic cycle involving a keto intermediate and HSSH production is found to be potentially viable. An alternative pathway, proceeding through an enol intermediate is found to exhibit similar energetic requirements. Non‐cyclical pathways, in which HSS. is generated in the final step instead of HS., show a markedly increased thermodynamic driving force (ca. 70 kJ mol?1) and thus warrant serious consideration in the context of the prebiotic ribonucleotide reduction. 相似文献
27.
Prof. Margaret A. Brimble Dr. Pat J. Edwards Dr. Paul W. R. Harris Dr. Gillian E. Norris Dr. Mark L. Patchett Tom H. Wright Dr. Sung‐Hyun Yang Dr. Sarah E. Carley 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(9):3556-3561
The first total synthesis of glycocin F, a uniquely diglycosylated antimicrobial peptide bearing a rare S‐linked N‐acetylglucosamine (GlcNAc) moiety in addition to an O‐linked GlcNAc, has been accomplished using a native chemical ligation strategy. The synthetic and naturally occurring peptides were compared by HPLC, mass spectrometry, NMR and CD spectroscopy, and their stability towards chymotrypsin digestion and antimicrobial activity were measured. This is the first comprehensive structural and functional comparison of a naturally occurring glycocin with an active synthetic analogue. 相似文献
28.
Experimental Evidence of Chemical Components in the Bonding of Helium and Neon with Neutral Molecules 下载免费PDF全文
29.
30.
N-Heterocyclic carbene catalysed redox isomerisation with reduction about the carbonyl has been developed in the transformation of trienyl esters to tetrasubstituted benzaldehydes. The reaction proceeds in good to excellent yield, and in cases that provide 2,2′-biaryls, enantioselectivity is observed. Mechanistic studies demonstrate the intermediacy of a cyclohexenyl β-lactone, while implicating formation of the homoenolate as turnover limiting. 相似文献